Collection_select returning multiple values

Rails
1

Hey,

Is is possible to make collection_select return multiple values? If yes,
how
can it be done?

IÂ?ve tried:

<%= collection_select(“group[]”, “id”, @groups, “id”, “name”,
{},{:multiple
=> true}) %>

Leading to:

You have a nil object when you didn’t expect it!

You might have expected an instance of ActiveRecord::Base.

The error occured while evaluating nil.id_before_type_cast

The @groups is Group.find(:all).

Can anyone help?

Thanks in advance,

Rúben Cabaço